The Facts on HVAC Filters

You’ve probably heard that changing out your HVAC filter on a regular basis is one of the best (and easiest) DIY services that you can do for your system. You may have even changed out the filter in the past 6 months – and then promptly forgotten about it. While changing out the filter is essential for keeping your HVAC running at optimum efficiency, there are several things to keep in mind to ensure that the effort has value. The consistency of the replacement (which varies during the year), the type of filter and the filter rating are all important components. We’ve broken down the essentials for you so that you can keep your system running smoothly throughout the winter season – and all year long.

Air Filter Replacement

Your HVAC filter is an essential part of your central air unit. A clean filter ensures that it runs efficiently and helps to clean the air in your home. So changing it out when it gets dirty sounds simple enough. But how often you will change out your own filter will depend on several factors. The number of people in your home, how many pets you own, the quality of air in your home and the air pollution in the city you live are all considerations. Inspecting your filter every month when not in heavy use (spring or fall) to get a handle on the amount of debris it catches is a good rule of thumb. But there are a few constants that you should keep in mind. During seasons when your HVAC is running continuously (usually in the summer and winter), you should change out the filter monthly. It is recommended that typical 1”-3” HVAC filters be changed bi-monthly, but depending on the factors mentioned, it might be more or less.

Air Filter Type

There are several different types of HVAC air filters available. Like any product on the market, some brands are better than others. Certain types need to be changed out every month in order to remain effective – while others might be viable for several years. The type you choose will depend on the annual usage of your HVAC, the basic size requirements and, of course, the cost. An HVAC technician will be able to recommend the best type of filter for your system, but it’s important to know the basic options if you ever need to replace a filter on your own.

Fiberglass – The most common type of air filter and also the least expensive. It is composed of layered fiberglass fibers supported by a metal grating. These are designed to catch large particles including dust and lint, but aren’t as efficient at catching airborne toxins and allergens. These filters are not effective at helping the indoor air quality (IAQ) and are not recommended for households dealing with allergy or asthma issues.

Polyester/Pleated – This is similar in design to fiberglass filters, but more effective in catching smaller particles. This design has a stronger resistance to airflow and typically needs to be changed more often (than the fiberglass models). A bit more expensive than fiberglass, the polyester/pleated filters are ideal for homes with pets and allergen issues.

Electrostatic – This type of filter is composed of electrically charged fibers that collect both large and small particles. It’s very effective at reducing airborne allergens and recommended for people who have severe allergies. Electrostatic filters are more expensive and not as easy to find, but most large home improvement stores keep them in stock.

Reusable Electrostatic – This is very similar to the disposable version, but doesn’t collect as many particles. It is considered more “green” because it is washable and lasts about six to eight years. Washable filters need to be dried thoroughly before they are used again to prevent mold.

Most HVAC air filters are given a performance rating issued from the Environmental Protection Agency (EPA). Called the Minimum Efficiency Reporting Value (MERV), this system rates the effectiveness of the filter on a scale of 1 to 16. The higher the MERV rating, the more efficient it is in collecting particles and airborne allergens. A typical household filter should have a minimum MERV rating of 7 (any number lower will only benefit the HVAC unit). MERV-rated brands that have a rating of 7 – 12 effectively remove airborne contaminants while anything rated higher is typically found in hospitals or healthcare facilities. A MERV rating higher than 12 might also be detrimental to your unit as the filters might make the system work harder to pull air through your ducts.

Using this information will help ensure healthier air and keep your HVAC performing at maximum efficiency. But remember that your filter is only one factor in your home’s IAQ. If you are changing out your filter on a regular basis, but are still suffering from problems related to your indoor air, contact Metro today. We specialize in air purification solutions and can help in dealing with factors unrelated to your filter. Call us today at 423-616-1025 or 706-516-1980 and we’ll schedule an appointment with an air quality specialist.